.math {
  margin: 1% auto;
}

.sub-title {
  font-size: 1rem;
}

.qr-code {
  width: 10rem;
  height: 10rem;
  display: flex;
  flex-direction: column;
  text-align: center;
  margin: 0;
  padding: 0;
}

.button-group {
  margin: 5rem 0;
  display: flex;
}

.button-group > button {
  font-size: 1rem;
  margin-right: 1rem;
}

.list {
  font-size: 1.4rem;
  display: flex;
  flex-wrap: wrap;
}
.list > li {
  width: 50%;
}
